Compact planar inverted F antenna

• US 6,218,991 B1
• Filed: 08/25/2000
• Issued: 04/17/2001
• Est. Priority Date: 08/27/1999
• Status: Expired due to Term

• Current Assignee: ARC Wireless, Inc. (ARC Group Worldwide, Inc.)
• Original Assignee: ARC Wireless Solutions, Incorporated
• Inventors: Sanad, Mohamed
• Primary Examiner(s): LE, HOANGANH T
• Application Number:
  US09/648,276
• Time in Patent Office: 235 Days
• Field of Search: H01/Q.138, 343/700.MS, 343/702, 343/846, 343/848, 343/829, 343/830, 343/831
• US Class Current: 343/700.0MS
• CPC Class Codes: H01Q 1/36 Structural form of radiating elements, e.g. cone, spiral, umbrella; Particular materials used therewithH01Q1/08, H01Q1/14 take precedence
• CPC Class Codes: H01Q 19/005 Patch antenna using one or more coplanar parasitic elements
• CPC Class Codes: H01Q 9/0421 with a shorting wall or a shorting pin at one end of the element H01Q9/0414 takes precedence
• CPC Class Codes: H01Q 9/0428 radiating a circular polarised wave

Abstract

A compact planar inverted F antenna suited for remote wireless metering includes a circuit element, a ground plane and a feed probe. The circuit element has a planar portion with a reactance window, and a narrowed tab that extends transverse to the planar portion and is connected to the ground plane. The reactance window and narrowed tab reduce the size of the circuit element. The feed probe is connected between the circuit element and the ground plane. The ground plane has conductive portions that are wrapped around a substrate to reduce the physical size of the ground plane. The length of the tab and thereby the distance between the planar portion and the ground plane is selected so that the feed probe is a radiating element. The antenna is compact with good isotropic characteristics and sensitivity to two perpendicular polarizations.

Claims

1. A compact planar inverted F antenna comprising:

a conductive circuit element including a planar portion and a tab extending transverse said planar portion, said planar portion having a first edge and a second edge spaced a selected first distance from said first edge, said tab having a first edge and a second edge spaced a selected second distance from said first edge, said second distance being at least 25% of said first distance, said first edge of said tab being connected to said first edge of said planar portion, and

a ground plane including planar conductive first, second and third portions,each having a first end and a spaced second end opposite said first end, said second and third portions being co-planar with said second ends of said second and third portions being opposite each other and separated by a gap, said second and third portions being spaced from and aligned with said first portion with said first end of said second portion being conductively connected to said first end of said first portion and said first end of said third portion being conductively connected to said second end of said first portion,

said second edge of said tab of said circuit element being connected to said first portion of said ground plane opposite said second and third portions, with said planar portion being aligned over and spaced at said second distance from said first portion of said ground plane.

2. The antenna of claim 1 wherein said first edge of said planar portion has a selected first width and said tab has a selected second width that is less than said first width.

3. The antenna of claim 1 wherein said planar portion includes a third edge between said first and second edges and a fourth edge opposite said third edge, and said planar portion includes a reactance window extending inward from said third edge toward said fourth edge.

4. The antenna of claim 1 including a feed probe,

said ground plane having a pad coplanar with and electrically isolated from said first portion and said feed probe being connected to said planar portion of said circuit element, extending transverse therefrom and being connected to said pad.

5. The antenna of claim 1 wherein said ground plane includes a dielectric substrate having a first side and a second side with said first portion of said ground plane being attached to said first side and said second and third portion being attached to said second side.

6. The antenna of claim 5 wherein said second and third portions of said ground plane are connected to first portion by vias extending through said substrate.

7. A compact planar inverted F antenna comprising:

a conductive circuit element including a planar portion and a tab each having a first edge and a spaced second edge opposite said first edge, said first edge of said tab being connected to said first edge of said planar portion with said tab extending transverse to said planar portion, said first edge of said planar portion having a selected first width and said tab having a selected second width that is less than said first width, said planar portion having a third edge between said first and second edges and a fourth edge opposite said third edge, said planar portion including a reactance window extending inward from said third edge toward said fourth edge,

a ground plane including a planar dielectric substrate, and conductive first, second and third portions each having a first end and a spaced second end opposite said first end, said substrate having a first and second side with said first portion being attached to said first side and said second and third portions being attached to said second side with said second ends of said second and third portions being opposite each other and separated by a gap, said first end of said second portion being conductively connected to said first end of said first portion through vias extending through said substrate and said first end of said third portion being conductively connected to said second end of said first portion through vias extending through said substrate, said second edge of said tab of said circuit element being connected to said first portion of said ground plane opposite said second and third portions, said second edge of said tab being spaced from said first end of said first portion with said planar portion aligned with said first portion of said ground plane and spaced from said first portion of said ground plane by a selected uniform distance that is at 25% the length of said planar portion from said first edge to said second edge, said ground plane including an opening in said first portion and a pad on said first side of said substrate within said opening, and

a feed probe connected to said planar portion of said circuit element intermediate said first edge and said reactance window and intermediate said third and fourth edges, said feed probe extending transverse to said planar portion of said circuit element and being connected to said pad on said ground plane.